Hey All, long time reader but 1st time poster. I have an M4700 and while brush hogging yesterday the temp gauge needle went all the to the cold side, almost laying flat. I checked fuses and some connections that I could see but I'm not a great mechanic. Any ideas would be greatly appreciated.
Temp gauge not working
- Thread starter GaryR
- Start date
Try removing the associated fuse and inserting again. It may just not be making good contact. While it's out check it for continuity with an ohmmeter. Sometimes they get tired and quit though still looking good. Your temperature sending unit in the block could be bad. If you can find what it should read at a given temperature you can check it with an ohmmeter. It is also possible a rodent chewed most of the way through a wire and finally broke while ;you were working. Of course the gauge itself could be defective, too
historically they're wired...
keyed +12 volts-->fuse--->-(pwr)temp guage(sens) <---------sensor---> ground
so, if you ground the temp guage sensor pin, the needle should go 'real hot' fairly fast. If it does, this confirms you've got a good guage and power to the guage.
hopefully you've got a wiring schematic for your tractor.....
keyed +12 volts-->fuse--->-(pwr)temp guage(sens) <---------sensor---> ground
so, if you ground the temp guage sensor pin, the needle should go 'real hot' fairly fast. If it does, this confirms you've got a good guage and power to the guage.
hopefully you've got a wiring schematic for your tractor.....
The L4700 is a model without readily available WSM info.
However, a parts check shows the same temp sensor used on other models where troubleshooting info is available.
I have attached the two pages showing how to test/trouble shoot the temp system on the L2250,L2550 & L2850 which will also cover most aspects of the L4700 temp system.
Dave
However, a parts check shows the same temp sensor used on other models where troubleshooting info is available.
I have attached the two pages showing how to test/trouble shoot the temp system on the L2250,L2550 & L2850 which will also cover most aspects of the L4700 temp system.
Dave
Thanks, now that I know what I'm looking for I can try testing it and see if I can find the issue when I get back there this weekend.
This occurred to my M4700 also….due to mice eating thru the wiring between the gauge and the sending unit when the previous owner had it. I simply spliced/inserted a new wire into the circuit to connect the WR wire from the gauge to the sending unit. (Used butt splices). Works great ever since.
The wiring schematic indicates the gauge-to-sender is a ”WR”…a White/Red wire. and gets its power from the combination switch thru a Red/Blue wire. (in the screen-shots below, item 2 is the “coolant temperature“ gauge.) The next pic is the data for the sending unit. Hope that helps.
The wiring schematic indicates the gauge-to-sender is a ”WR”…a White/Red wire. and gets its power from the combination switch thru a Red/Blue wire. (in the screen-shots below, item 2 is the “coolant temperature“ gauge.) The next pic is the data for the sending unit. Hope that helps.
Yeah, GaryW, I hate the lack of a proper Table of Contents or Index in the WSM…but the tractor wiring diagram/schematic is in Section 9M-1, starting on pg 355. PM me if you don’t have the WSM.
OK so here's where I'm at sorry to say. So far electrical seems OK, fuses good, wires are OK but can't see much of them. I think I found the sensor which is on the right side toward the rear of the block. I am now stuck trying to pull the steering wheel so I can remove the dash to get at the gouges. I have a puller but it seems really stuck!! Any ideas?
OK, Gary…. loosen the steering-wheel shaft nut…but LEAVE IT. on the shaft by a few threads. Using a common puller apply a “strain” on the wheel to pull it off….and “whack” the nut with a brass mallet or an ordinary hammer using a piece of wood against the nut. The wheel will “pop” off.
Otherwise, you must either buy the special tool…or MAKE on…..(it’s not hard)… a piece of flat plate steel shaped like a “U” with the slot in the ”U” wide enough to slip down thru the shaft. Then using the puller to pull up on the “U” instead of the plastic steering wheel.
Otherwise, you must either buy the special tool…or MAKE on…..(it’s not hard)… a piece of flat plate steel shaped like a “U” with the slot in the ”U” wide enough to slip down thru the shaft. Then using the puller to pull up on the “U” instead of the plastic steering wheel.
But FIRST…. disconnect the wire from the sending unit and connect it to GROUND (engine block, etc) with the key ”ON” to see if the gauge reads HOT.
If it does then the problem is the sending unit. If it doesn’t…. the problem is the gauge or the wire connection between the gauge and sending unit…or the gauge isn’t receiving power with the key “on”.
If it does then the problem is the sending unit. If it doesn’t…. the problem is the gauge or the wire connection between the gauge and sending unit…or the gauge isn’t receiving power with the key “on”.
Here's what I got on the steering wheel
I've tried hitting the top of the center shaft on the puller but to no avail. Î put a lot of pressure on the puller and some WD and I am hoping it might loosen overnight. I will try grounding the wire and see what happens. Thanks for riding along with me on this.
I've tried hitting the top of the center shaft on the puller but to no avail. Î put a lot of pressure on the puller and some WD and I am hoping it might loosen overnight. I will try grounding the wire and see what happens. Thanks for riding along with me on this.
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Gary, that’s exactly the same tool I used and I agree…it didn’t want to come off until I smacked that jack-screw in the center of the tool while it had taken a strain on the center nut/shaft. It eventuallhy “popped” off. (There’s simply no need to tighten that nut down as tight as some folks think…and a little anti-seize on the splines when you re-install it is appropriate.
I’m sure you saw the steering-wheel removal tool pic I posted above…. you can make that plate pretty easy.
I’m sure you saw the steering-wheel removal tool pic I posted above…. you can make that plate pretty easy.
Well maybe I'll find that the sensor is bad and won't even have to pull the wheel. I'll post tomorrow and let you know.
Thanks guys, got the steering wheel off and wouldn't you know it, after testing the gage it's the sensor. So will pick up a new one when I'm back in town and be done with it. I'm going to replace the ign switch since the dash is tore down. Any thing else I should do while it's apart.
Think about what other improvements you might wish to do while the inst cluster is off…. I added an Ammeter on the lower-left, and two rocker switches (O’Reillys) on the right side (to power two L.E.D. LIghtbars….one up front and one facing the rear)… and a flashing-red indicator light (O’Reillys) operated by the parking-brake lock-lever so I’d quit trying to drive the tractor with the parking brake set. LOL.
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Gary, let me add that I didn’t like the fact the M4700 uses the Low-Fuel warning light as a charge-indicator light. If that light illuminates it means one of two things… either you’re down to only 2 gals of diesel…or the alternator/charging system is inoperative.
By adding an ammeter (Harbor Freight sells a whole set of auto gauges for less than $20 and I stole the ammeter out of the set) to the lower left of the instrument panel … I can see the glow-plugs draw a 20A discharge during each start ….and can see the alternator immediately re-charge the battery after each start. None of that info is otherwise available to a M4700 owner.
(Yes, the GPs heat up during each ordinary start when the key is turned to the start position. Of course, you probably already know that to heat them up manually all you do is turn the key to the left of the “off” postion. Again…an ammeter will confirm their operation… otherwise you’d just have to ”trust”.)
How ‘bout posting a picture of your tractor?
By adding an ammeter (Harbor Freight sells a whole set of auto gauges for less than $20 and I stole the ammeter out of the set) to the lower left of the instrument panel … I can see the glow-plugs draw a 20A discharge during each start ….and can see the alternator immediately re-charge the battery after each start. None of that info is otherwise available to a M4700 owner.
(Yes, the GPs heat up during each ordinary start when the key is turned to the start position. Of course, you probably already know that to heat them up manually all you do is turn the key to the left of the “off” postion. Again…an ammeter will confirm their operation… otherwise you’d just have to ”trust”.)
How ‘bout posting a picture of your tractor?
Oh man Geohorn, you must be clairvoyant, the low fuel light has been on for about 6 months. I talked to the dealer about it and he said it was probably a bad diode and as long as the fuel gage was working not to worry about it. Sooo, the question is, what is the easiest way to check the charging system? I can't thank you enough for helping.
easiest ?
put voltmeter on battery,write down the voltage ( say it's 13.3)
now start up the tractor,,write down the voltage ( say it's 15.7), battery is being charged....
what normall happens is the battery voltage will 'dip down' to say 10ish then climb up(16ish) once running for awhile.
what the actual numbers are and how fast it 'recovers' depends on lots of things like condition of battery, GP used or not, wiring, alt/genny output, temperature, etc.
now if you want... buy my Snap-On alternator tester...it's show you lots of good info, old schoolwise.
put voltmeter on battery,write down the voltage ( say it's 13.3)
now start up the tractor,,write down the voltage ( say it's 15.7), battery is being charged....
what normall happens is the battery voltage will 'dip down' to say 10ish then climb up(16ish) once running for awhile.
what the actual numbers are and how fast it 'recovers' depends on lots of things like condition of battery, GP used or not, wiring, alt/genny output, temperature, etc.
now if you want... buy my Snap-On alternator tester...it's show you lots of good info, old schoolwise.